研究者詳細 - 久保田　翔

Overexpression of Hmga2 activates Igf2bp2 and remodels transcriptional program of Tet2-deficient stem cells in myeloid transformation. 査読国際誌

Jie Bai, Takako Yokomizo-Nakano, Sho Kubota, Yuqi Sun, Akinori Kanai, Mihoko Iimori, Hironori Harada, Atsushi Iwama, Goro Sashida

Oncogene 40 ( 8 ) 1531 - 1541 2021年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

High Mobility Group AT-hook 2 (HMGA2) is a chromatin modifier and its overexpression has been found in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Level of Hmga2 expression is fine-tuned by Lin28b-Let-7 axis and Polycomb Repressive Complex 2, in which deletion of Ezh2 leads to activation of Hmga2 expression in hematopoietic stem cells. To elucidate the mechanisms by which the overexpression of HMGA2 helps transformation of stem cells harboring a driver mutation of TET2, we generated an Hmga2-expressing Tet2-deficient mouse model showing the progressive phenotypes of MDS and AML. The overexpression of Hmga2 remodeled the transcriptional program of Tet2-deficient stem and progenitor cells, leading to the impaired differentiation of myeloid cells. Furthermore, Hmga2 was bound to a proximal region of Igf2bp2 oncogene, and activated its transcription, leading to enhancing self-renewal of Tet2-deficient stem cells that was suppressed by inhibition of the DNA binding of Hmga2. These combinatory effects on the transcriptional program and cellular function were not redundant to those in Tet2-deficient cells. The present results elucidate that Hmga2 targets key oncogenic pathways during the transformation and highlight the Hmga2-Igf2bp2 axis as a potential target for therapeutic intervention.

DOI： 10.1038/s41388-020-01629-w

Src-mediated tyrosine phosphorylation of PRC1 and kinastrin/SKAP on the mitotic spindle. 査読国際誌

Mariko Morii, Sho Kubota, Chizu Hasegawa, Yumi Takeda, Shiori Kometani, Kyoko Enomoto, Takayuki Suzuki, Sayuri Yanase, Rika Sato, Aki Akatsu, Kensuke Hirata, Takuya Honda, Takahisa Kuga, Takeshi Tomonaga, Yuji Nakayama, Noritaka Yamaguchi, Naoto Yamaguchi

Scientific reports 11 ( 1 ) 2616 - 2616 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

Src-family tyrosine kinases (SFKs) play important roles in a number of signal transduction events during mitosis, such as spindle formation. A relationship has been reported between SFKs and the mitotic spindle; however, the underlying mechanisms remain unclear. We herein demonstrated that SFKs accumulated in the centrosome region at the onset of mitosis. Centrosomal Fyn increased in the G2 phase in a microtubule polymerization-dependent manner. A mass spectrometry analysis using mitotic spindle preparations was performed to identify tyrosine-phosphorylated substrates. Protein regulator of cytokinesis 1 (PRC1) and kinastrin/small kinetochore-associated protein (kinastrin/SKAP) were identified as SFK substrates. SFKs mainly phosphorylated PRC1 at Tyr-464 and kinastrin at Tyr-87. Although wild-type PRC1 is associated with microtubules, phosphomimetic PRC1 impaired the ability to bind microtubules. Phosphomimetic kinastrin at Tyr-87 also impaired binding with microtubules. Collectively, these results suggest that tyrosine phosphorylation of PRC1 and kinastrin plays a role in their delocalization from microtubules during mitosis.

DOI： 10.1038/s41598-021-82189-1

Calreticulin haploinsufficiency augments stem cell activity and is required for onset of myeloproliferative neoplasms in mice. 査読国際誌

Kotaro Shide, Takuro Kameda, Ayako Kamiunten, Yoshinori Ozono, Yuki Tahira, Takako Yokomizo-Nakano, Sho Kubota, Masaya Ono, Kazuhiko Ikeda, Masaaki Sekine, Keiichi Akizuki, Kenichi Nakamura, Tomonori Hidaka, Yoko Kubuki, Hisayoshi Iwakiri, Satoru Hasuike, Kenji Nagata, Goro Sashida, Kazuya Shimoda

Blood 136 ( 1 ) 106 - 118 2020年7月

記述言語：英語掲載種別：研究論文（学術雑誌）

Mutations in JAK2, myeloproliferative leukemia virus (MPL), or calreticulin (CALR) occur in hematopoietic stem cells (HSCs) and are detected in more than 80% of patients with myeloproliferative neoplasms (MPNs). They are thought to play a driver role in MPN pathogenesis via autosomal activation of the JAK-STAT signaling cascade. Mutant CALR binds to MPL, activates downstream MPL signaling cascades, and induces essential thrombocythemia in mice. However, embryonic lethality of Calr-deficient mice precludes determination of a role for CALR in hematopoiesis. To clarify the role of CALR in normal hematopoiesis and MPN pathogenesis, we generated hematopoietic cell-specific Calr-deficient mice. CALR deficiency had little effect on the leukocyte count, hemoglobin levels, or platelet count in peripheral blood. However, Calr-deficient mice showed some hematopoietic properties of MPN, including decreased erythropoiesis and increased myeloid progenitor cells in the bone marrow and extramedullary hematopoiesis in the spleen. Transplantation experiments revealed that Calr haploinsufficiency promoted the self-renewal capacity of HSCs. We generated CALRdel52 mutant transgenic mice with Calr haploinsufficiency as a model that mimics human MPN patients and found that Calr haploinsufficiency restored the self-renewal capacity of HSCs damaged by CALR mutations. Only recipient mice transplanted with Lineage-Sca1+c-kit+ cells harboring both CALR mutation and Calr haploinsufficiency developed MPN in competitive conditions, showing that CALR haploinsufficiency was necessary for the onset of CALR-mutated MPNs.

DOI： 10.1182/blood.2019003358

Low prevalence of the BCR-ABL1 fusion gene in a normal population in southern Sarawak. 査読

Jew Win Kuan, Anselm Ting Su, Siow Phing Tay, Isabel Lim Fong, Sho Kubota, Lela Su'ut, Motomi Osato, Goro Sashida

International journal of hematology 111 ( 2 ) 217 - 224 2020年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

The BCR-ABL1 fusion gene is the driver mutation of Philadelphia chromosome-positive chronic myeloid leukemia (CML). Its expression level in CML patients is monitored by a real-time quantitative polymerase chain reaction defined by the International Scale (qPCRIS). BCR-ABL1 has also been found in asymptomatic normal individuals using a non-qPCRIS method. In the present study, we examined the prevalence of BCR-ABL1 in a normal population in southern Sarawak by performing qPCRIS for BCR-ABL1 with ABL1 as an internal control on total white blood cells, using an unbiased sampling method. While 146 of 190 (76.8%) or 102 of 190 (53.7%) samples showed sufficient amplification of the ABL1 gene at > 20,000 or > 100,000 copy numbers, respectively, in qPCRIS, one of the 190 samples showed amplification of BCR-ABL1 with positive qPCRIS of 0.0023% and 0.0032% in two independent experiments, the sequence of which was the BCR-ABL1 e13a2 transcript. Thus, we herein demonstrated that the BCR-ABL1 fusion gene is expected to be present in approximately 0.5-1% of normal individuals in southern Sarawak.

DOI： 10.1007/s12185-019-02768-x

Ascl1-induced Wnt11 regulates neuroendocrine differentiation, cell proliferation, and E-cadherin expression in small-cell lung cancer and Wnt11 regulates small-cell lung cancer biology. 査読国際誌

Yuki Tenjin, Shinji Kudoh, Sho Kubota, Tatsuya Yamada, Akira Matsuo, Younosuke Sato, Takaya Ichimura, Hirotsugu Kohrogi, Goro Sashida, Takuro Sakagami, Takaaki Ito

Laboratory investigation; a journal of technical methods and pathology 99 ( 11 ) 1622 - 1635 2019年11月

記述言語：英語

The involvement of Wnt signaling in human lung cancer remains unclear. This study investigated the role of Wnt11 in neuroendocrine (NE) differentiation, cell proliferation, and epithelial-to-mesenchymal transition (EMT) in human small-cell lung cancer (SCLC). Immunohistochemical staining of resected specimens showed that Wnt11 was expressed at higher levels in SCLCs than in non-SCLCs; 58.8% of SCLC, 5.2% of adenocarcinoma (ADC), and 23.5% of squamous cell carcinoma tissues stained positive for Wnt11. A positive relationship was observed between Achaete-scute complex homolog 1 (Ascl1) and Wnt11 expression in SCLC cell lines, and this was supported by transcriptome data from SCLC tissue. The expression of Wnt11 and some NE markers increased after the transfection of ASCL1 into the A549 ADC cell line. Knockdown of Ascl1 downregulated Wnt11 expression in SCLC cell lines. Ascl1 regulated Wnt11 expression via lysine H3K27 acetylation at the enhancer region of the WNT11 gene. Wnt11 controlled NE differentiation, cell proliferation, and E-cadherin expression under the regulation of Ascl1 in SCLC cell lines. The phosphorylation of AKT and p38 mitogen-activated protein kinase markedly increased after transfection of WNT11 into the SBC3 SCLC cell line, which suggests that Wnt11 promotes cell proliferation in SCLC cell lines. Ascl1 plays an important role in regulating the Wnt signaling pathway and is one of the driver molecules of Wnt11 in human SCLC. Ascl1 and Wnt11 may employ a cooperative mechanism to control the biology of SCLC. The present results indicate the therapeutic potential of targeting the Ascl1-Wnt11 signaling axis and support the clinical utility of Wnt11 as a biological marker in SCLC.

DOI： 10.1038/s41374-019-0277-y

Role for tyrosine phosphorylation of SUV39H1 histone methyltransferase in enhanced trimethylation of histone H3K9 via neuregulin-1/ErbB4 nuclear signaling 査読

Nakajo, H., Ishibashi, K., Aoyama, K., Kubota, S., Hasegawa, H., Yamaguchi, N., Yamaguchi, N.

Biochemical and Biophysical Research Communications 511 ( 4 ) 765 - 771 2019年4月

Desuppression of TGF-β signaling via nuclear c-Abl-mediated phosphorylation of TIF1γ/TRIM33 at Tyr-524, -610, and -1048 査読

Ryuzaburo Yuki, Takashi Tatewaki, Noritaka Yamaguchi, Kazumasa Aoyama, Takuya Honda, Sho Kubota, Mariko Morii, Ichiro Manabe, Takahisa Kuga, Takeshi Tomonaga, Naoto Yamaguchi

Oncogene 38 ( 5 ) 637 - 655 2018年9月

Ezh2 loss propagates hypermethylation at T cell differentiation-regulating genes to promote leukemic transformation. 査読国際誌

Changshan Wang, Motohiko Oshima, Daisuke Sato, Hirotaka Matsui, Sho Kubota, Kazumasa Aoyama, Yaeko Nakajima-Takagi, Shuhei Koide, Jun Matsubayashi, Makiko Mochizuki-Kashio, Takako Nakano-Yokomizo, Jie Bai, Toshitaka Nagao, Akinori Kanai, Atsushi Iwama, Goro Sashida

The Journal of clinical investigation 128 ( 9 ) 3872 - 3886 2018年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Early T cell precursor acute lymphoblastic leukemia (ETP-ALL) is a new pathological entity with poor outcomes in T cell ALL (T-ALL) that is characterized by a high incidence of loss-of-function mutations in polycomb repressive complex 2 (PRC2) genes. We generated a mouse model of ETP-ALL by deleting Ezh2, one of the PRC2 genes, in p53-null hematopoietic cells. The loss of Ezh2 in p53-null hematopoietic cells impeded the differentiation of ETPs and eventually induced ETP-ALL-like disease in mice, indicating that PRC2 functions as a bona fide tumor suppressor in ETPs. A large portion of PRC2 target genes acquired DNA hypermethylation of their promoters following reductions in H3K27me3 levels upon the loss of Ezh2, which included pivotal T cell differentiation-regulating genes. The reactivation of a set of regulators by a DNA-demethylating agent, but not the transduction of single regulator genes, effectively induced the differentiation of ETP-ALL cells. Thus, PRC2 protects key T cell developmental regulators from DNA hypermethylation in order to keep them primed for activation upon subsequent differentiation phases, while its insufficiency predisposes ETPs to leukemic transformation. These results revealed a previously unrecognized epigenetic switch in response to PRC2 dysfunction and provide the basis for specific rational epigenetic therapy for ETP-ALL with PRC2 insufficiency.

DOI： 10.1172/JCI94645

Src Acts as an Effector for Ku70-dependent Suppression of Apoptosis through Phosphorylation of Ku70 at Tyr-530 査読

Mariko Morii, Sho Kubota, Takuya Honda, Ryuzaburo Yuki, Takao Morinaga, Takahisa Kuga, Takeshi Tomonaga, Noritaka Yamaguchi, Naoto Yamaguchi

JOURNAL OF BIOLOGICAL CHEMISTRY 292 ( 5 ) 1648 - 1665 2017年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Src-family tyrosine kinases are widely expressed in many cell types and participate in a variety of signal transduction pathways. Despite the significance of Src in suppression of apoptosis, its mechanism remains poorly understood. Here we show that Src acts as an effector for Ku70-dependent suppression of apoptosis. Inhibition of endogenous Src activity promotes UV-induced apoptosis, which is impaired by Ku70 knockdown. Src phosphorylates Ku70 at Tyr-530, being close to the possible acetylation sites involved in promotion of apoptosis. Src-mediated phosphorylation of Ku70 at Tyr-530 decreases acetylation of Ku70, whereas Src inhibition augments acetylation of Ku70. Importantly, knockdown-rescue experiments with stable Ku70 knockdown cells show that the nonphosphorylatable Y530F mutant of Ku70 reduces the ability of Ku70 to suppress apoptosis accompanied by augmentation of Ku70 acetylation. Our results reveal that Src plays a protective role against hyperactive apoptotic cell death by reducing apoptotic susceptibility through phosphorylation of Ku70 at Tyr-530.

DOI： 10.1074/jbc.M116.753202

Src family kinases maintain the balance between replication stress and the replication checkpoint 査読

c-Abl-mediated Tyrosine Phosphorylation of JunB is Required for Adriamycin-induced Expression of p21. 査読

Noritaka Yamaguchi, Ryuzaburo Yuki, Sho Kubota, Kazumasa Aoyama, Takahisa Kuga, Yuuki Hashimoto, Takeshi Tomonaga, Naoto Yamaguchi

The Biochemical journal 471 ( 1 ) 67 - 77 2015年10月

Takahito Miura, Yasunori Fukumoto, Mariko Morii, Takuya Honda, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

Cell Biology International 40 ( 1 ) 16 - 26 2015年8月

Imatinib inhibits inactivation of the ATM/ATR signaling pathway and recovery from adriamycin/doxorubicin-induced DNA damage checkpoint arrest 査読

Mariko Morii, Yasunori Fukumoto, Sho Kubota, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

CELL BIOLOGY INTERNATIONAL 39 ( 8 ) 923 - 932 2015年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

The DNA damage checkpoint arrests cell cycle progression to allow time for DNA repair. After completion of DNA repair, checkpoint activation is terminated, and cell cycle progression is resumed in a process called checkpoint recovery. The activation of the checkpoint has been studied in depth, but little is known about recovery from the DNA damage checkpoint. Recently we showed that Src family kinases promote recovery from the G2 DNA damage checkpoint. Here we show that imatinib inhibits inactivation of ATM/ATR signaling pathway to suppress recovery from Adriamycin/doxorubicin-induced DNA damage checkpoint arrest. Imatinib and pazopanib, two distinct inhibitors of PDGFR/c-Kit family kinases, delayed recovery from checkpoint arrest and inhibited the subsequent S-G2-M transition after Adriamycin exposure. By contrast, imatinib and pazopanib did not delay the recovery from checkpoint arrest in the presence of an ATM/ATR inhibitor caffeine. Consistently, imatinib induced a persistent activation of ATR-Chk1 signaling. By the way, the maintenance of G2 checkpoint arrest is largely dependent on ATR-Chk1 signaling. However, unlike Src inhibition, imatinib did not delay the recovery from checkpoint arrest in the presence of an ATM inhibitor KU-55933. Furthermore, imatinib induced a persistent activation of ATM-KAP1 signaling, and a possible involvement of imatinib in an ATM-dependent DNA damage response is suggested. These results reveal that imatinib inhibits recovery from Adriamycin-induced DNA damage checkpoint arrest in an ATM/ATR-dependent manner and raise the possibility that imatinib may inhibit resumption of tumor proliferation after chemo- and radiotherapy.

DOI： 10.1002/cbin.10460

c-Abl induces stabilization of histone deacetylase 1 (HDAC1) in a kinase activity-dependent manner 査読

Overexpression of Zinc-Finger Protein 777 (ZNF777) Inhibits Proliferation at Low Cell Density Through Down-Regulation of FAM129A. 査読

Ryuzaburo Yuki, Kazumasa Aoyama, Sho Kubota, Noritaka Yamaguchi, Shoichi Kubota, Hitomi Hasegawa, Mariko Morii, Xiayu Huang, Kang Liu, Roy Williams, Michiko N. Fukuda, Naoto Yamaguchi

Journal of cellular biochemistry 116 ( 6 ) 954 - 968 2015年6月

Kazumasa Aoyama, Noritaka Yamaguchi, Ryuzaburo Yuki, Mariko Morii, Sho Kubota, Kensuke Hirata, Kohei Abe, Takuya Honda, Takahisa Kuga, Yuuki Hashimoto, Takeshi Tomonaga, Naoto Yamaguchi

39 ( 4 ) 446 - 456 2015年1月

Lyn tyrosine kinase promotes silencing of ATM-dependent checkpoint signaling during recovery from DNA double-strand breaks 査読

Yasunori Fukumoto, Kazumasa Kuki, Mariko Morii, Takahito Miura, Takuya Honda, Kenichi Ishibashi, Hitomi Hasegawa, Sho Kubota, Yudai Ide, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 452 ( 3 ) 542 - 547 2014年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

DNA damage activates the DNA damage checkpoint and the DNA repair machinery. After initial activation of DNA damage responses, cells recover to their original states through completion of DNA repair and termination of checkpoint signaling. Currently, little is known about the process by which cells recover from the DNA damage checkpoint, a process called checkpoint recovery. Here, we show that Src family kinases promote inactivation of ataxia telangiectasia mutated (ATM)-dependent checkpoint signaling during recovery from DNA double-strand breaks. Inhibition of Src activity increased ATM-dependent phosphorylation of Chk2 and Kap1. Src inhibition increased ATM signaling both in G2 phase and during asynchronous growth. shRNA knockdown of Lyn increased ATM signaling. Src-dependent nuclear tyrosine phosphorylation suppressed ATM-mediated Kap1 phosphorylation. These results suggest that Src family kinases are involved in upstream signaling that leads to inactivation of the ATM-dependent DNA damage checkpoint. (C)2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2014.08.113

v-Src inhibits the interaction between Rad17 and Rad9 and induces replication fork collapse 査読

Yasunori Fukumoto, Takahito Miura, Mariko Morii, Sho Kubota, Takuya Honda, Shoichi Kubota, Takao Morinaga, Noritaka Yamaguchi, Yuji Nakayama, Naoto Yamaguchi

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 450 ( 1 ) 885 - 890 2014年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

ATR-dependent DNA damage checkpoint is crucial to maintain genomic stability. Recently, we showed that Src family kinases suppress ATR-dependent checkpoint signaling in termination of DNA damage checkpoint. However, the precise molecular mechanism is unclear. Therefore, we examined the role of oncogenic v-Src on ATR-Chk1 signaling. We show that v-Src suppresses thymidine-induced Chk1 phosphorylation and induces replication fork collapse. v-Src inhibits interaction between Rad17 and Rad9 in chromatin fraction. By contrast, v-Src does not inhibit RPA32 phosphorylation, ATR autophosphorylation, or TopBP1-Rad9 interaction. These data suggest that v-Src attenuates ATR-Chk1 signaling through the inhibition of Radl7-Rad9 interaction. (C) 2014 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2014.06.078

Src Family Kinases Promote Silencing of ATR-Chk1 Signaling in Termination of DNA Damage Checkpoint 査読

Yasunori Fukumoto, Mariko Morii, Takahito Miura, Sho Kubota, Kenichi Ishibashi, Takuya Honda, Aya Okamoto, Noritaka Yamaguchi, Atsushi Iwama, Yuji Nakayama, Naoto Yamaguchi

JOURNAL OF BIOLOGICAL CHEMISTRY 289 ( 18 ) 12313 - 12329 2014年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Background: Once DNA repair is completed, the DNA damage checkpoint is terminated, and the cell cycle is resumed. Results: Src inhibition induced a delay in G(2) checkpoint recovery and persistent ATR-Chk1 activation. Conclusion: Src inhibits ATR signaling to promote recovery from G(2) checkpoint arrest. Significance: Src sends a termination signal between the completion of DNA repair and the initiation of checkpoint termination.
The DNA damage checkpoint arrests cell cycle progression to allow time for repair. Once DNA repair is completed, checkpoint signaling is terminated. Currently little is known about the mechanism by which checkpoint signaling is terminated, and the disappearance of DNA lesions is considered to induce the end of checkpoint signaling; however, here we show that the termination of checkpoint signaling is an active process promoted by Src family tyrosine kinases. Inhibition of Src activity delays recovery from the G(2) phase DNA damage checkpoint following DNA repair. Src activity is required for the termination of checkpoint signaling, and inhibition of Src activity induces persistent activation of ataxia telangiectasia mutated (ATM)- and Rad3-related (ATR) and Chk1 kinases. Src-dependent nuclear protein tyrosine phosphorylation and v-Src expression suppress the ATR-mediated Chk1 and Rad17 phosphorylation induced by DNA double strand breaks or DNA replication stress. Thus, Src family kinases promote checkpoint recovery through termination of ATR- and Chk1-dependent G(2) DNA damage checkpoint. These results suggest a model according to which Src family kinases send a termination signal between the completion of DNA repair and the initiation of checkpoint termination.

DOI： 10.1074/jbc.M113.533752